Gestational Diabetes – Causes, Diagnosis, Consequences

An occurrence observed statistically in nearly 18% of women while carrying a baby is the onset of gestational diabetes during pregnancy (GDM). While a woman with diagnosed type 1 or type 2 diabetes has the opportunity to prepare with particular caution when planning a pregnancy, excluding the possibility of conception until stable compensation of carbohydrate metabolism is achieved for at least 2–4 months before conceiving, the development of gestational diabetes cannot be predicted with absolute certainty.

A completely different situation arises when diabetes is first detected during an existing pregnancy and is a result of changes occurring in the pregnant woman’s body. However, the presence of any, including chronic, illnesses in the expectant mother to some extent poses a threat to the health of the developing baby. 

What is diabetes and how it occurs

To understand why diabetes is dangerous during pregnancy, it’s necessary to figure out what this condition is. Diabetes is an endocrine disease in which a chronic high level of glucose in the blood occurs due to a relative or absolute insulin deficiency. Insulin is a protein-peptide hormone produced by the pancreas. This hormone is responsible for maintaining normal blood glucose levels and allows its delivery to the cells of the tissues for their nourishment. 

In the development of diabetes mellitus, metabolic processes are disrupted. Depending on the type of disease, either the body loses sensitivity to insulin or the pancreas does not produce it in sufficient quantities. As a result, glucose accumulates in the blood without reaching the cells. Consequently, tissues experience energy starvation.

Types of Diabetes Mellitus

Considering the reason for the disruption of glucose transport, it is customary to distinguish:

• Type 1 diabetes mellitus – develops due to insulin deficiency, requiring the patient to take insulin-containing drugs because the pancreas fails to produce enough insulin;
• Type 2 DM – its origin lies in insulin resistance, meaning the cells are insensitive to the hormone despite its sufficiency in the body, resulting in the failure of glucose transportation;
• gestational – this diabetes develops during pregnancy and in most cases resolves after childbirth, posing a health risk to the mother and fetus.

The condition characterized by reduced glucose tolerance is called prediabetic and is considered separately. Since fasting sugar does not exceed normal limits, the deviation is detected after a glucose load.

How Gestational Diabetes is Diagnosed

Women who have not previously had diabetes may not even be aware that with the onset of pregnancy, they have developed gestational diabetes mellitus (GDM). It is identified because, when registering for prenatal care, a blood glucose test is mandatory and its level is constantly monitored. To diagnose gestational diabetes during pregnancy, an initial fasting venous blood sample is taken. The normal range is considered to be 3.3-5.1 mmol/L. If these levels are exceeded, a glucose tolerance test or glucose load test is prescribed. 

The analysis consists of two stages. First, a standard fasting test is taken. Then the woman drinks a solution containing 75 g of glucose, and after 2 hours, the test is repeated. If suspicions remain, the test is conducted again in a few hours. A diagnosis of GDM is confirmed if fasting blood glucose is between 5.1-7 mmol/L, and more than 8.5 mmol/L two hours after taking 75 g of glucose.

Who is at risk

Unfortunately, gestational diabetes during pregnancy can develop in a completely healthy woman, which is why it is necessary to visit a doctor regularly and not skip recommended screenings. However, there are also risk factors associated with:

• having close relatives with diabetes;
• being older than 30 or younger than 18;
• multiple pregnancy;
• polycystic ovary syndrome;
• lack of physical activity;
• presence of a large amount of simple carbohydrates in the diet;
• having harmful habits – alcohol abuse, smoking;
• being overweight and obese, which definitely lead to metabolic disturbances;
• previously giving birth to a child weighing over 4 kg;
• during the current pregnancy – a large fetus;
• a history of gestational diabetes or prediabetes, the predisposition to which does not disappear over time.

Symptoms of Gestational Diabetes

Gestational diabetes during pregnancy typically develops between the 15th and 20th weeks. Detection in early stages indicates that the woman already had type I or II diabetes before pregnancy. The main issue with detecting gestational diabetes during pregnancy is that it generally lacks the symptoms characteristic of type 1 and 2 diabetes. In most cases, the disease is asymptomatic, which is extremely dangerous for both the mother and the fetus. 

Pronounced symptoms of gestational diabetes are quite rare and are all nonspecific. For example, the expectant mother may experience increased thirst and related consumption of more than 2 liters of water a day, dry mouth, weight loss or gain. Pregnant women may complain of increased urination (polyuria), itching in the genital area, as well as lack of energy, appetite changes, fatigue, weakness, and decreased activity.

Why gestational diabetes is dangerous during pregnancy

The development of gestational diabetes during pregnancy is a pathological condition that poses a threat to the health of both the expectant mother and baby. This is because the fetus begins to actively produce insulin to compensate for the elevated glucose levels in the mother’s blood even before birth. As a result, such children are prone to low blood sugar from birth. Furthermore, they are at higher risk of developing type II diabetes and obesity in adulthood. 

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Gestational diabetes during pregnancy adds an additional risk factor for the development of preeclampsia – a severe form of gestosis, characterized by high blood pressure. Symptoms of preeclampsia include sluggishness, headaches, vision problems, nausea, vomiting, insomnia, or drowsiness. It is one of the most severe disorders affecting the central nervous system, which can be triggered by gestational diabetes during pregnancy.

What other possible consequences

Another concerning factor associated with gestational diabetes during pregnancy is the rapid weight gain of the baby in the intrauterine period – macrosomia. This subsequently leads to difficulties during childbirth and poses a threat to the mother’s health. If the baby’s weight exceeds 4 kg, the risk of birth injuries increases, and in such cases, a cesarean section is more likely to be necessary. 

Large fetal size can lead to the need for forced delivery before the due date, with an increased risk of premature birth.

Consequences of elevated sugar in pregnant women also include an increased risk of conditions that make it difficult for the baby to breathe (respiratory distress syndrome), nervous and cardiovascular pathologies of the fetus, generally increasing the risk and frequency of complications during pregnancy and childbirth.

How to treat

The first step in treating gestational diabetes during pregnancy is moderate physical activity and a balanced diet. The goal is to reduce blood sugar to normal levels. Patients with all signs of GDM need a full range of minerals and vitamins necessary for proper fetal development and maintaining their own health. Recommendations include frequent meals in small portions, avoiding fatty pastries and fast food, and adding a variety of fresh vegetables, grains, and lean meats to the diet. An absolute taboo is food with a high glycemic index (bananas, grapes, sugar, white bread). 

Beneficial activities include water aerobics, walking, therapeutic physical exercises, and swimming. If physical activity and diet do not lead to a reduction in blood sugar levels, insulin therapy is prescribed. High blood sugar requires daily glucose level measurements, taken with a home glucometer one hour after each meal and on an empty stomach.

Diabetes and Childbirth

Diabetes during pregnancy is a serious threat not only to carrying a child but also poses a risk of complications during childbirth. Data from recent studies conducted by scientists from Wayne University in the USA have shown that the optimal period for delivery with gestational diabetes in pregnant women is the 39th–40th week of gestation. Experts believe that this period minimizes the risk of operative vaginal delivery for the mother and the development of distress syndrome in the child. Inducing labor at a later term often has negative consequences and may even have adverse neonatal outcomes. 

Inducing labor before the 39th week is recommended only if there is a specific symptom present. This could be a rupture of the fetal membranes, hypertensive disorder, or deterioration in the baby’s vital signs. It is also possible in the case of ineffective glycemic control, which significantly increases the risk of stillbirth.

Prevention in Pregnant Women

Unfortunately, there are no entirely effective ways to prevent gestational diabetes. However, the more healthy habits a woman adopts before and in the early stages of pregnancy, the more successful the pregnancy and delivery will be. 

Namely:

• from the very first days, consume foods low in fat and high in fiber, prioritizing whole-grain products and vegetables;
• monitor portion sizes and strive for variety;
• dedicate at least half an hour to exercise every day;
• take daily walks, swim, ride a bike;
• plan pregnancy at a normal weight, avoid excessive and rapid weight gain – this increases the risk of gestational diabetes during pregnancy.

A healthy lifestyle, despite the lack of universal protection against GDM, will help reduce the risk of its occurrence. It is very important to detect its signs in time and prevent the condition from developing.